The other 11 months Washington's a town of No. 1s, so in August, the No. 2s try harder.

At the Embassy of Indonesia last night, where an elaborate celebration marking the 36th anniversary of Indonesian independence was underway, that meant such eclectic groupings as:

* The No. 2 men from the embassies of Czechoslovakia, India and Malaysia huddled in one corner.

* The No. 2 man from Sri Lanka and the Soviet Embassy's newly arrived Asian specialist together in another corner.

* The No. 2 man from the Australian Embassy and the assistant secretary of state for East Asian affairs together near the food.

Reunions were commonplace. Australia's Geoffrey Price, minister and deputy chief of mission, and Assistant U.S. Secretary of State John H. Holdridge had known other since both served in Singapore. Similarly, the Soviet Union's Yuri Arkharov was catching up on the good old days in Sri Lanka, where he and P.M.D. Fernando, Sri Lanka's deputy chief of mission here, first met.

On the surface, international concerns seemed to take a back seat to culinary ones such as lumpia (egg rolls), shrimp tempura, sate with peanut sauce and rempeyek, the near-addictive peanut-filled pastry clusters that, like everything else on the two buffet tables, had been made at home earlier in the day by embassy wives.

Among Ambassador and Mrs. D. Ashari's nearly 500 guests were Secretary of the Army John O. Marsh Jr. and the ambassadors of Saudi Arabia, Laos, Thailand, the Philippines and Singapore.

Col. Djarot Supadmo, Indonesia's military attache', provided inquiring guests with an instant recap of Indonesian independence. "When the United States dropped the atomic bomb in 1945 and the Japanese surrendered, on the 17th of August we seized Japanese arms and fought another four years against the Dutch and British," he said.

Which brought up the subject of Indonesia's military might today. At some 240,000 men, Supadmo admitted it was small in relation to its 152,000,000 population (fifth largest in the world).

"But we don't see any threat, not yet. We feel insurgency may be the threat and, if so, our military can handle it."

Said Ambassador Ashari of regional problems: "One concern is the Cambodian issue. That's why we as members of ASEAN Association of South East Asian Nations are trying for a political solution in the United Nations. We have to be patient with Vietnam."